Apparatus for removing suspended materials from gas streams



Sept. 6, 1955 s. G. ANDRES 2,717,051

APPARATUS FOR REMOVING SUSPENDED MATERIALS FROM GAS STREAMS Filed Feb. 1, 1952 4 Sheets-Sheet 1 3a, 49 H I O I I z 3M 5 Q ]IO/ 38 I8 3| 34 45 32 27- l h w 48 E 37 a 34 29 4:

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i I ZNVENTOR :2 l3 STANLEY c. ANDRES ATTORNEYS Sept. 6, 1955 s. G. ANDRES 2,717,051

APPARATUS FOR REMOVING SUSPENDED MATERIALS FROM GAS STREAMS Filed Feb. 1. 1952 4 Sheets-Sheet 2 INVENTOR STANLEY G. ANDRES ATTORNEYS Sept- 6, 1955 s. G. ANDRES 2,717,051

APPARATUS FOR REMOVING SUSPENDED MATERIALS FROM GAS STREAMS Filed Feb. 1, 1952 4 Sheets-Sheet IS INVENTOR STANLEY G. ANDRES BY JM 2% ATTORNEYS Sept. 6, 1955 s. G. ANDRES 2,717,051

APPARATUS FOR REMOVING SUSPENDED MATERIALS FROM GAS STREAMS Filed Feb. 1, 1952 4 Sheets-Sheet 4 7 III T INVENTOR STANLEY G. ANDRES ATTORNEYS United States Patent APPARATUS FOR REMOVING SUSPENDED MATERIALS FROM GAS STREAMS Stanley G. Andres, Metuchen, N. J assignor to Research Corporation, New York, N. Y., a corporation of New York Application February 1, 1952, Serial No. 269,524

4 Claims. (Cl. 1837) This invention relates to apparatus for removing suspended materials from gas streams and more particularly to a combined mechanical and electrostatic separator wherein the elements are housed in a unitary casing.

An object of the invention is to provide apparatus for removing suspended particulate material, such as dust, fly ash,-mist, tar, and the like, from gas streams bearing the same.

Another object is to provide such apparatus that is of compact construction and wherein the mechanical and electrical separating sections are superimposed one upon .1

the other, whereby only a small base or ground area is required to accommodate the apparatus and good gas distribution is attained.

Another object is to provide apparatus of this type that eificiently cleans gas streams that carry suspended material having a wide range of particle size.

These, and other objects as may appear hereinafter, are realized in apparatus for separating from a gas stream particulate material suspended therein which includes a vertically extending casing, means defining a gas inlet chamber intermediate the top and bottom of the casing, the chamber having a gas inlet opening, a plurality of centrifugal gas cleaning devices positioned in the casing below the chamber, each gas cleaning device having a gas inlet communicating with the chamber, a gas outlet conduit extending through the chamber to a point of discharge in the casing above the chamber, and an opening below the chamber for discharge of material collected in the centrifugal cleaning device, gas outlet means in the casing above the chamber, complementary discharge and collecting electrodes positioned in the casing above the chamber in the stream of gas discharged from the plurality of gas cleaning devices and flowing to the gas outlet means, means in the casing above the chamber receiving dust collected by the collecting electrodes, and conduit means extending downwardly from the receiving means conveying dust therefrom to a discharge point below the chamber.

The apparatus of the invention may take a number of variant forms, some of which are shown in the drawings wherein:

Fig. l is a vertical sectional view of one form of apparatus for removing suspended materials from gas streams;

Fig. 2 is a horizontal sectional view taken along the line 22 of Fig. 1;

Fig. 3 is a partial vertical sectional view taken along the line 33-of Fig. 1;

Fig. 4 is a front elevational view of another form of apparatus embodying the invention, portions being broken away to show interior construction;

Fig. 5 is a right hand elevational view of the apparatus of Fig. 4, parts being broken away for similar reasons;

Fig. 6 is a view similar to Fig. 4 of still another form of apparatus in accordance with the invention;

Fig. 7 is a right hand elevational view of the apparatus IJI iCC

of Fig. 6 with parts broken away to show interior construction; and

Fig. 8 is a side elevational view of yet another form of apparatus in accordance with the invention; parts being broken away.

Referring to the drawings, particularly to Figs. 1,. 2 and 3 thereof, the combined mechanical and electrical separator shown is especially adapted for the separation and collection of fly ash from furnaces and boilers. The apparatus has a vertically extending casing or shell 10 that is'rectangular in horizontal cross-section. walls converge at the bottom of the casing toform a pyramidal hopper 11 having a dust outlet 12 cIosed' by a sliding gate 13.

A gas duct 14 conducts gas to be cleaned to the apparatus, the gas being admitted to the casing through an inlet opening 15 formed in one wall of the casing 10.

Beneath the opening 15 a horizontal diaphragm" plate 16 is disposed across the'entire area of the casing. An inclined diaphragm plate 17 extends from just above the opening 15 to a line of juncture 18 with the horizontal plate 16 adjacent the casing wall opposite the opening 15. The inclined plate extends across the casing from one .side wall to the other. Between the two diaphragm plates and included portions of the casing side walls is defined a gas inlet chamber 19.

Suspended from the lower'diaphragmpl'ate 16 are gas cleaning devices designated by the general reference numeral 20. As shown, these gas cleaning devices are of the mechanical type and specifically are conventional cyclone separators. Each cyclone separator has a cylindrical casing 21 tapering at the bottom 22 to adust outlet 23 discharging into the hopper 11. Gas is admitted to the separator 20 from the chamber 19throughan'opening 24 and is given the usual swirling motion by fixed vanes 25. A gas outlet pipe 26 extends axially of the cylinder 21 from about the mid-point of the cylinder upwardly through the chamber 19and through a hole inthe diaphragm plate 17 to terminate in a discharge end 27. Bafiles 28 affixed to the upper end of pipe 26 serve to'distribute the gas issuing from the pipe so that the gas spreads out in the horizontal direction and does not channel through the upper section of the apparatus.

' Suspended in the casing above the diaphragm plate 1 7 are vertically extending parallel extended surface collector electrodes 29. These electrodes are hung from brackets 30 secured to the walls of the casing 10. The collecting electrodes are of the box type having hollow interiors. Horizontal troughs 31 extend across the vertical surfaces of the electrodes at spaced intervals; these troughs receive dust that is dislodged from the electrode surfaces when the electrodes are rapped orvibrated as by actuation of a rapping device 32 connected to the collector electrodes by a vibration-transmitting rod 33. The troughs 31 communicate with the hollow interiors of the box electrodes through suitable openings and dust that is received in the troughs falls into the spaces in the box electrodes, and down through the interior spaces into the hopper bottoms 34. .Dust chutes 35, 36- convey the dust from the hopper bottoms 34 through star valvesv 37 to vertical pipes 38, 39. Pipes'38 and 39 extend downwardly through holes in the diaphragm plates 16 and 17 and terminate in discharge ends 40, 41 inthe' main dust hopper 11.

Discharge electrode wires 42 are hung from a framework 43 carried by insulators 4'4 supported in the top of the casing. Ten'sioning Weights 45 attached tothe bottoms of the discharge wires serve to hold the wires taut. It will be understood that curtains of discharge wires are disposed in the spaces intermediate adjacent collector electrodes and that the discharge and collector electrodes are complementary to each other and co- Patented Sept. 6,. 1955 The side operate to provide charging and precipitation conditions when energized from a suitable source of high potential electric current. Customarily, the discharge wires are energized from the negative pole of the current source through wires 46 and the collector electrodes are grounded through their supporting members. The energizing circuit is completed by grounding the positive pole of the current source.

An opening 47 for discharge of cleaned gas from the apparatus is provided in the top of the casing 10.

A spray device 48 in the inlet duct 14 and a similar spray device 49 in the gas inlet chamber 19 are used to humidify and precondition the gas for the purpose of improving collection efficiency.

In operation of the apparatus of Figs. 1 to 3, the complernentary electrodes 29 and 42 are energized, the spray devices 48 and 49 are put in operation, and the star valves 37 are actuated by rotating the shaft 50 by a suitable motor (not shown). Gas to be cleaned, for

example boiler flue gases containing suspended fly ash,

is caused to flow from the duct 14 into the gas inlet chamber 19. In the duct 14'and chamber 19, the gas is sprayed with water from the spray devices 48 and 49 and is cooled, humidified and conditioned for further treatment. The suspended fly ash has a wide range of particle size, the larger particles being gritty and the smaller particles being of fine smoke size.

From the inlet chamber 19, the dust laden gas flows into the cyclone separators 20 wherein the larger and gritty particles are removed by centrifugal action in a manner well known in the art. The dust removed in the cyclone separators falls through openings 23 into the hopper 11 and the gas containing the remainder of the dust passes upwardly through pipes 26 and is distributed evenly in the upper section of the apparatus by the baffles 28.

The gas next flows upwardly between the collector electrodes 29 where it is subjected to electrical precipitation conditions and is substantially freed of its fine ash burden. Cleaned gas leaves the apparatus through the outlet 47.

Dust that is precipitated on the collector electrodes 29 is removed therefrom by actuation of the rapper 32. This dust is caught in the troughs 31 and falls by gravity into the hollows of the collector electrodes, down through the chutes 35 and 36, through the star valves 37 and down throughthe pipes 38, 39 into the hopper 11 where it commingles with the dust from the cyclone separators 20. The star valves 37 allow the dust to pass downwardly through the chute system while substantially preventing reverse flow of gas therethrough.

Dust is removed from the hopper as necessary through the gate 13.

Referring to Figs. 4 and 5, the gas cleaning apparatus shown is similar to that shown in Figs. 1 to 3 with the following principal differences: (1) dust from the cyclone separators is received in a hopper system separate from the hopper that receives dust from the collector electrodes, and (2) the dust chutes that convey dust from the collector electrodes do not pass through the gas inlet chamber; instead the'dust chutes are located at the sides of the gas inlet chamber.

Since the forms of apparatus of Figs 1 to 3 and Figs. 4 and 5 are so much alike, primed reference numerals are used in Figs. 4 and 5 to designate parts that are similar to corresponding parts in Figs. 1 to 3 having the same, but unprimed, reference numerals.

In Figs. 4 and 5, ll) designates the casing having a hopper 11' and dust outlet 12'. A gas inlet opening 15' admits gas to be cleaned to the gas inlet chamber 19'. Cyclone separators 20 have inlet openings 24 communicating with the chamber 19 and gas outlet pipes 26' delivering partially cleaned gas to the electrical precipitation section. Dust from the cyclone separators falls into the hoppers 51 through openings 23 in the bottoms of the cyclone separators.

The hoppers 51 may be discharged into the hopper 11 through star valves 52 driven by shaft 53 and motor 54. However, if it is desired to collect separately the dust from the cyclone separators and that from the electrical precipitation section, a separate dust outlet (not shown) may be provided for the hoppers 51.

Gas from the mechanical collectors fiows between the collector electrodes 29 and complementary discharge electrodes 42' and out of the apparatus through the outlet opening 47'.

Dust collected in the box electrodes 29 falls into the hopper 3.1 through the chute system including pipes 36, 38 and 39'.

The star valves 52 allow dust to pass from hoppers 51 to hopper 11' While preventing gas from flowing from the hoppers 51 to the hopper 11' and up through the dust chute pipes 39.

Operation of the apparatus of Figs. 4 and 5 is believed to be obvious from a consideration of the structure and the analogous operation of the apparatus of Figs. 1 to 3 as described hereinbefore.

Referring to Figs. 6 and 7, the gas cleaning apparatus therein shown is similar to that shown in the figlres described hereinbefore. It differs primarily from the form of Figs. 1 to 3 in that the dust from the cyclone separators is collected in a hopper system separate from the hopper system that receives dust from the electrical precipitation section. Whereparts in the apparatus of Figs. 6 and 7 correspond to similar parts in the forms of apparatus described hereinbefore, such parts are designated in Figs. 6 and 7 by corresponding double-primed reference numerals.

The casing 16" has a gas inlet opening 15" for admission to the apparatus of gas to be cleaned. The gas inlet chamber 19" is trapezoidal in cross-section, as seen in Fig. 6, and is defined by the lower diaphragm plate 16" and the upper arched diaphragm plate assembly 17". Cyclone separators 20" are suspended from the lower diaphragm plate 16" and discharge dust and grit into the hopper system 11". Partially cleaned gas from the cyclone separators passes by way of outlet pipes 26 into a chamber 55 included between a perforated gas distributing plate 56 and the hoppers 57. The hoppers 57 receive dust from the collecting electrodes 29" of a superposed electrical precipitator that is positioned in the casing 10" above the gas distributing plate 56. Dust flows from the collecting electrodes to the hoppers 57 through the conduits 38" that pass through suitable openings in the gas distributing plate 56.

Complementary discharge electrodes 42" are associated with the collecting electrodes 29" in the electrical precipitator section of the gas cleaning apparatus. Cleaned gas leaves the apparatus through the outlet 47".

From the preceding description, the manner of operation of the apparatus of Figs. 6 and 7 is believed to be apparent.

The forms of apparatus shown in Figs. 1 to 7 are especially adapted to the collection of dry dust, particularly fly ash from coal burning boilers and the like. Where it is desired to separate the coarse material from the fine, the apparatuses of Figs. 6 and 7 or 4 and 5 are most useful. Such separation may be desired in case the coarse fraction of fly ash can be reused for burning and the fine fraction cannot be so used.

Referring to Fig. 8, the gas cleaning apparatus therein shown may be used for the collection of wet or dry suspended material from gases but is peculiarly adapted to the collection of wet or tarry materials. The apparatus is similar in many respects to that shown in Figs. 1 to 3; it differs therefrom in that it has a liquid filled sump and the chutes from the collecting electrodes do not pass through the gas inlet chamber. In the following description of Fig. 3, triple primed reference numerals refer to parts having counterparts in Figs. 1 to 3 that are designated by the same but unprimed reference numerals.

The gas cleaning apparatus of Fig. 8 has a housing 10 having a gas inlet leading to a gas inlet chamber 19" defined by a horizontal lower diaphragm plate 16" and an inclined upper diaphragm plate 17". Cyclone separators 20" depend from the lower diaphragm plate 16 and discharge material separated therein through bottom openings 23 into the hopper or sump 11". Partially cleaned gas issues from the cyclone gas discharge pipes 26' into the space above the upper diaphragm plate 17".

The bottom opening 12' of the sump 11" is connected to an inverted syphon leg 58 that overflows into a vertical liquid discharge pipe 59. Liquid level in the sump is thus maintained at the level of the overflow connection between the syphon leg 58 and discharge pipe 59.

The electrical precipitation section of the apparatus includes the hollow collecting electrodes 29 and the complementary discharge electrodes 42". The hollow collecting electrodes drain through down spouts 38" into a common pipe 60 that discharges into a conduit 61 the lower end 62 of which is submerged in the pool of liquid 63 in the sump 11". Because the conduit opening 62 is submerged in the pool of liquid, a gas tight liquid seal is maintained at this point preventing short-circuiting fiow of gas from the sump up through the conduit 61.

Gas issuing from the cyclone discharge pipes 26" passes up through the electrical precipitation section where it is subjected to a final electrostatic cleaning action. Clean gas is discharged from the apparatus through the outlet 47".

In operation, particles of fog or mist that are collected in the cyclone separators 20" drip into the sump 11" through the bottom openings 23". Additional particles of mist that are collected on the extended surface electrodes 29" flow by gravity into the interiors of the electrodes and thence through the pipes 38", 60 and 61 to the sump 11".

It will be apparent that the common receiving pipe 60 can be eliminated where mist or fog is collected. In this case, the liquid issuing from downcomers 38" drips onto the inclined diaphragm plate 17" and flows down the plate into the conduit 61 and thence to the sump 11".

Where dry dusty material is collected in the apparatus of Fig. 8, the sump will be filled with water or other appropriate liquid from an independent source. The inclined common receiving pipe 60 preferably is used when dry dust is collected.

I claim:

l. An apparatus for separating suspended particulate material from a gas stream comprising, a vertically extending casing, single particulate material receiving hopper at the lower end of said casing, a horizontal header plate extending across the casing above the hopper, an inclined header plate in said casing cooperating with said horizontal header to define a dirty gas inlet into said casing, mechanical gas cleaning means insaid casing,

said mechanical gas cleaning means having gas inlet means communicating with the dirty gas inlet and gas outlet means discharging into said casing above said inclined header means, particulate material discharge means from said mechanical gas cleaning means into the single particulate material receiving hopper, a complementary dis charge and collecting electrode system positioned in said casing vertically above the inclined headerplate and the stream of gas discharged from said mechanical gas cleaning means, means including conduits conveying material collected by the collecting electrodes to the particulate material receiving hopper below the mechanical gas cleaning means whereby material collected by both the mechanical gas cleaning means and on the collecting electrodes is discharged to and collected in the same material receiving hopper; clean gas outlet means above the complementary discharge and collecting electrode system, and means in said casing preventing gas flow from said particulate material receiving hopper to the complementary discharge and collecting electrode system whereby the gas stream to be cleaned must pass serially through the mechanical gas cleaning means and between the complementary discharge and collecting electrodes.

2. The invention as defined in claim 1 wherein said means preventing gas flow from said hopper to the complementary discharge and collecting electrodes comprises valve means in the conduits conveying material collected by the collecting electrodes to said hopper.

3. The invention as defined in claim 1 wherein said means preventing gas flow from said hopper to the complementary discharge and collecting electrodes comprises, means including conduits conveying particulate material from the mechanical gas cleaning means to the particulate material receiving hopper, and valve means in said conduits.

4. The invention as defined in claim 1 wherein said means preventing gas flow from said hopper to the complementary discharge and collecting electrodes comprises a liquid containing sump means in said particulate material receiving hopper and means maintaining the liquid level in said sump above the discharge end of the conduits conveying material collected from the collecting electrodes.

References Cited in the file of this patent UNITED STATES PATENTS 1,508,331 Huber Sept. 9, 1924 1,970,048 Marshall Aug. 14, 1934 1,997,125 Soyez et al. Apr. 9, 1935 2,372,514 Pootjes Mar. 27, 1945 2,399,509 Rich Apr. 30, 1946 2,542,549 McBride Feb. 20, 1951 2,554,247 Hedberg May 22, 1951 FOREIGN PATENTS 498,355 Belgium Jan. 15, 1951 

